There are two different images:
Store / catalog logo (the mark we drop onto standard bag mockups): 1500 × 1500 px, square, transparent PNG if you can.
Custom label art (your full bag design): 1600 × 2400 px for regular bags, 600 × 900 px for 2oz. That file is the whole label, not just the logo.
If the logo looks small in the white box on a standard bag, send a tighter crop at 1500 × 1500. We cannot stretch a 1024 × 1024 file to fill the box cleanly.
Charity or extra copy on a standard logo bag still has to stay inside that logo area. For a full-bleed design, use a custom label.